Question of the Day #11

"How far is the library?"
"About 3 kilometers as the crow flies."

上記の会話で、as the crow fliesは、どういう意味？
In the dialogue above, what does "as the crow flies" mean?

答えは、コメントに書いてください。
Write your answer in the Comments.

明日、ここに答えを書きます。
I will write the answer and other remarks here tomorrow.

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解答

意味： 一直線に、直線・最短距離で

Answer:

In a direct line, without any of the detours caused by following a road.

語源：

カラスは、最短距離で飛ぶ習性があると言われていることから。
World Wide Wordsによると、最も古い使用例は、1761年の下記英文とのこと。

Etymology:

According to World Wide Words:

Anyone who has watched a crow flying any distance knows it tends to do so in a steady, unwavering line — not always, but then this is a generalisation of a tendency, not invariable fact. Since the flight of the crow is unaffected by obstacles on the ground, its route came to represent the shortest distance between two points.
This is the earliest example I’ve so far found:

Now the country that those Indians inhabit is upwards of 400 miles broad, and above 600 long, each as the crow flies.
The Gentleman’s and London Magazine, Dec. 1761.

Examples

• It is 15 kilometers as the crow flies.
• 'How far is it from Cambridge to London?' 'About 50 miles as the crow flies.'
• Our farm is only five miles from town as the crow flies, but the winding roads mean we have to drive nearly eight miles to get there.
• It’s only three miles to Square Tower as the crow flies, but it’s all of ten miles if the Glasgow Hamilton Road is closed and one has to drive round the Johnstone Road.